Cement slurries are used in the oil and gas industries, such as for cementing in oil and gas wells. Primary, remedial, squeeze, and plug cementing techniques can be used, for instance, to place cement sheaths in an annulus between casing and well formations, for well repairs, well stability, or for well abandonment (sealing an old well to eliminate safety hazards). These cement slurries must be able to consistently perform over a wide range of temperatures and conditions as cement set in an oil and gas well may be vulnerable to cyclic stresses imposed by pressure and temperature fluctuations. A brittle cement may crack and break under these stresses, reducing the integrity of the wellbore.